Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

EGR - 1992 deville

I think I am having EGR problems on a 1992 deville, I think. Can I just disconnect the vacuum line and plug it to see if it is the problem. Please help. Engine kind of shutters at times under slight acceleration. Then if i put my foot in it has all the power I need. But once every few weeks when it is hot outside( for the most part) and I put my foot in it it will cut out while stumbling. Plugs look great right gap. Wires look good. Ideas?

EGR valves are only open under steady-state cruising when there is moderate to high manifold vacuum. They are closed at idle and they are closed under heavy accelleration…You can safely disconnect them but your CEL nag light might come on…

Would the light appear with a code if I plugged the vac line while trying to figure out what is wrong. My plan would be to clear the codes plug the line and drive it to see if the problem is gone and if it throws a code.

Be advised that most EGR problems are caused by carbon buildup that keeps the valve in the open position. If this happens, simply disconnecting the vacuum line will not show the real problem.

The EGR system in your vehicle is called a Back Pressure Induced EGR system. This means you have to provide exhaust back pressure to the EGR valve to test it.

A quick way to determine if there’s a problem with the EGR system is, once the engine is up to operating temperature and shut off, take a something like a large socket that almost restricts the exhaust and along with a pair of Vise-Grips clamp the socket into the tip of the exhaust pipe to restrict the exhaust flow. Now try starting the engine. If the engine starts but runs rough there may be a problem with the EGR circuit. If you want to see if the EGR circuit is working properly, then you would leave the socket in the tail pipe. Remove the vacuum hose from the EGR valve and connect a hand vacuum pump into the hose. Start the engine and apply vacuum to the EGR valve. If the engine starts to stumble or dies when vacuum is applied to the EGR valve, the EGR valve is working properly.


Un plug EGR problem goes away problem solved. Probably not the problem. Ignition more lilely, or TPS. Known for worn distributor drive gears causing timing fluctuation. TPS (throttle position sensor) would wear in that range causing signal drop out, hesitation stumble, stall. You need a lab scope or a graphing multi meter to determine this

How could I check the tps? The car has 105K on it. I believe it is called an HEI distributor. The one with the coil in it.

will it throw a code indicating tps?

Again…you’ll need a LAB scope or graphing multi meter on the signal wire from the TPS. Looking for a clean sweep from .5 volts to 4.5 V with no drop outs or spikes. Concentrate on the throttle position in which the problem occurs.

same problem with my 95 toyota corolla, replaced the EGR, still hiccuping around 65mph, more so if the car is not warmed up…

will it throw a code indicating tps?

not on a 92…not for glitchs anyway

Today I plugged the vacuum EGR line. Drive it for about 5 miles in overdrive. Seemed to do okay, maybe still a little shuttering. I drove it in second gear for about 5 miles after wiping out the carbon in the throttle body then spraying it with cleaner. It seemed to run great.

I noticed that after the first 1/2 inch the throttle position sensor no longer comes in contact with the piece the attaches the cable to the throttle body. I am not sure what that would be called, cable lobe? I am assuming that is why it ran well in second when the cables pull more cable.

Also when I was spraying the throttle body while the car was running and the cable lobe was released and came in contact with the sensor. The sensor would take about three second to retract in back to its original position. This cause the RPMs to dope slowly. It seems a little weird.

Does this tell you anything?

I want to thank everyone for their help. It is appreciated.

That thing is called an idle speed control motor. The sensor is mounted to the throttle body. The switch at the end of the plunger is a idle contact switch to let the pcm know to take over the idle.

should i just replace tps? and see if that works? I just do not want to keep throwing parts and money that are not needed.